Malick



Oct. 25, 1955 E. A. MALlcK 2,721,890

INDICATING AND CONTROL DEVICE Filed Dec. 10, 1951 THRESHOLD 28a V| (DE CE L A CI-D 29% :D

ATT NEY United States Patent .if

INDICATING AND CONTROL DEVICE T Em'l A. Malick, Bartlesville, Gkla., assignor to Phillips Petroleum Company, a corporation of Delaware ,Application December 10, 1951, Serial No. 260,889

13 Claims. (Cl. 12S-146.5)

This 'invention relates to an apparatus for detecting after firing or backliring in an internal combustion engine. In another aspect, it relates to an automatic control system for suppressing afterring or backring.

In accordance with this invention, I position a flame dettector in. the exhaust line of an internal combustion tengine, this detector incorporating a ceramic member so Patented Oct. 25, 1955 is', a timevx du'rin'g each cycle at which the ignition spark constructed that a potential difference is produced between :spaced points therein when a flame impinges upon the [ceramic :material. Heretofore, it has been proposed to place ,a .fhermocouple or like element in the exhaust line in an effort to detect afterring or backring. VThe derector of this invention is much more simple and quick *v to respond than a therrnocouple, and it vis capable of producing a large power output, as compared to that of a thermncouple, also insensitive to temperature.

, The output produced by the ame detector may control i such operating lire variables of the engine as might effect the condition of either afterring or backiring, when such corrected conditions are the same for both afterring or backliring, or, in some cases, Where the apparatus is capable-of distinguishing between the two.

It is an object of the invention to provide an improved Vsystem for detecting afterfiring or backring in an internal (combustion engine.

It is a further object to provide an automatic control :system of novel construction for the suppression of after- ;iring or backring.

It is a still further object to provide a system which is ;reliable in operation, economical to manufacture, and is (extremely quick acting.

Various other objects, advantages and features of the invention Will become apparent from the following detailed description taken in conjunction with the accompartying drawings, in which:

Figure 1 is a top view of an internal combustion engine utilizing the control system of this invention; and

Figure 2 is a detailed view of the name detector and associated servomechanism.

Referring now to the drawings in detail, I have shown an internal combustion engine 10 having a plurality of cylinders to which ring current is supplied by spark plugs 11 connected by leads 12 to a distributor 13. Engine 10 may be any of various types, such as a in line aircraft engine, a marine or other stationary type, and it may be powered by gasoline, a heavy oil, or any other suitable type of fuel. The engine 10 is provided with an exhaust manifold 14 which collects combustion gases'from the for utilizing such power. The engine has an intake manifold 16a, Figure 2, for supplying a fuel-air mixture to the intake valves of the cylinders.

The engine 10 is also providedwith an operating lever `17 controlling a suitable operating variable of the engine M which aiects afterburning, afterflring or backiring, as

-jiereafter dened. In a preferredv embodiment ofthe OCCUI'S.

In accordance with` th'e invention, ajiame detector 20 is/ provided to detect the presence o'f name in the' exhaust pipe 15. This detector includes a rounded, generally hemispherical head 21 formed from ceramic' material and positioned within the exhaust pipe 15. A cylindrical shield 22 of refractory conductive material, such as stainless steel, has one end thereof xedly secured to the head 21. To this end, a series of circumferentially spaced openings 23 are formed in the lower end of shield 22, and portions of the head 21 protrude through these openings to hold the parts in assembled relation. Mounted within the shield 22 is an electrode 24 having a hook-shaped end portion 25 embedded in the ceramic head 21. An insert 26 of refractory insulating material is disposed within the shield 22 and serves to support the outer end of electrode 24.

When a flame impinges upon the ceramic head 21, the electrical charges carried by the ions impinging upon the ceramic head produce a current ow with the result that an electrical output is produced by the detector until the ionic charges are dissipated. If desired, this electrical output may be fed through a threshold device 27 to an indicator 28 which, by indicating when an electrical output is present, shows directly whether or not a ame is impinging upon the head 21. Threshold device 27 may consist of a biased rectifier which eliminates electrical outputs of less than a predetermined amplitude, such as those resulting from the presence of stray currents in the vicinity of the flame detector. Rectification of the electrical output is desirable in order that either positive or negative charges may be eliminated from the ame detector output. Otherwise, the current ow produced by positive and negative charges mightbalance out over a period of time, thereby giving a zero indication even when a flame Was impinging upon the detector. Such a threshold device is shown in detail by U. S. Patent No. 2,448,323, Serial No. 458,757, to D. R. deBoisblanc, entitled Detonation Meter.

Alternatively, in accordance with the invention, the electrical output of the detector is utilized through suitable servomechanism to automatically regulate the spark advance, or other suitable variable o f the engine, in such fashion as to suppress or minimize afterring, afterburning or backring. i

This servomechanism can include an amplifier 28a fed by theshold device 27, the output of the amplifier being fed, in turn, to an operating winding 29 of a solenoid 30 having a reciprocable plunger 31. A valve stem 32 is secured to plunger 31, and this valve stem is Slidable in an annular valve chamber 33. Hydraulic uid, such as oil, under pressure is supplied to a central opening 34 of the chamber by a line 35. Chamber 33 also has drain holes 36, 37 at the respective opposite ends thereof from which hydraulic fluid can be fed to drain sumps by lines 38 and 39, respectively. Valve chamber 33 is also supplied with an opening 40 intermediate openings 34 and 37 together with an opening 41 intermediate openings 3:4 and 36. Valve stem 32 is provided with a flange 42 which is normally positioned between openings 34, 4t) and a ange 43 which is normally positioned between openings 36, 41.

Cooperating with the hydraulic valve is a piston mech- .anism 45 including a piston chamber 46 defined by an a bore 53 and a pipe 54 to the opening 40 in hydraulic valve 33 while the other end of the piston Chamber is connected through a bore 55y and a line 56 to the openingi41 in valve chamber 33.

As hereinbefore stated, it is the purpose of this invention to detect afterring, afterburning or backiiring and to regulate a suitable operating variable of the engine in such fashion as to suppress or minimize such conditions. Backtiring is defined herein as combustion which takes place upstream of the intake valve inl the induction systeni of the engine. Such a condition can cause complete los's of aircraft engines through burning of the induction system members, occasionally leading to fire in the accessory section of the nacelle, which has in some cases caused complete loss of an aircraft and its occupants. Such a condition can be detected, in accordance with this invention, by inserting a probe of the described type in the intake manifold 16a.

Afterfiring, as used herein, means combustion which takes place downstream of the exhaust valve, as in the exhaust collector or manifold, or in the exhaust pipe or muffler in an automobile engine. In one type of afterfirin'g, referred to herein as afterburning, combustion continues to take place within the cylinder during a period when the exhaust valve is open, the zone of combustion extending through the exhaust valve into the downstream portion of the exhaust system. Such a condition can be detected by a probe placed downstream of the exhaust valve, as in Figure l. In another type of afterfiring, combustion of unburned fuel is initiated in a downstream part of the exhaust system by contact of the material with hot metal surfaces or hot gases. To detect this condition, the probe should be placed a substantial distance downstream from the exhaust valve in the exhaust system and, in such location, afterburning may also be detected.

In the operation of the system for the detection of backfiring, the probe is positioned in intake manifold 16a, as shown by Figure 2. Backring causes a flame to irn- Vpinge upon the ceramic head of the detector with the result that a signal passes through threshold device 27 and amplifier 28 to a suitable indicating device, not shown, which informs the operator of the potentially dangerous backfier 28a can be used to actuate suitable control mechanism firing conditions. Alternatively, the signal from ampli- -to regulate a suitable operating variable of the engine to suppress or eliminate the backfiring conditions, in the manner hereinafter described.

When the principles of the invention are applied to the detection and correction of undesirable afterfiring conditions, the probe is located in the exhaust system downstream of the exhaust valve in the manner previously explained. Of course, a plurality of probes can be used, one for the detection of backfiring and another .for the detection of afterfiring. Alternatively, separate probes can be provided in the exhaust system to detect afterburning or to provide a regulating action when only a mild condition of afterfiring exists. With the parts in the position shown, there is no afterfiring, with the result that spark control lever 17 is in its normal position and the flame detector is not actuated. Under these conditions, oil under pressure passes from line 35 through the annulus between flanges 42, 43 and line S6 to the outer portion of piston chamber 46, thereby urging the piston inwardly and maintaining the spark lever in its normal position.

`Whe`n afterfiring occurs, a iiame impinges upon `the ceramic head 21 with the result that an electrical output is produced by detector 20 which passes through threshold device 27 and amplifier 28a to energize solenoid 30, thereby raising valve stem 32 to a position where flange 42 'is positioned between openings 37, 40 and flange 43 is positioned between openings 34, 41. Thereupon, fluid under pressure passes from line 35 through the'annulus between flanges 42, 43 and thence by way `of pipe.54,

-and bore 53 to the piston chamber, with the result that piston 49 is moved outwardly thus displacing spark control lever 17 and advancing the spark to correct the undesirable afterfiring condition. During this period, oil in the outer portion of the piston chamber can drain through line 56 and the lower portion of the valve chamber 33 to drain pipe 38.

When afterfiring ceases, no output is produced by detector 20 with the result that valve stem 32 returns to the position shown in Figure 2, thereby returning piston 49 to its inner position and moving the spark control 17 to its original position. During this return movement of the piston, the oil at the inner end of the chamber drains through pipe 54, and the upper part of valve chamber 33 to drain pipe 39.

It will be apparent that I have provided a completely automatic system for suppressing afterfiring or backfiring in an internal combustion engine. The system is very reliable and quick acting, due to the large output produced by flame detector 20 when a llame is incident upon the ceramic head 21. Moreover, even when the servomechanism is eliminated, a reliable and rapid indication of the presence of flame in exhaust pipe 15 is obtainable.

While the invention has been described in connection with a present, preferred embodiment thereof, it is to be understood that this description is illustrative only and is not intended to limit the invention, the scope of which is defined by the appended claims.

I claim:

l. The combination, with an internal combustion engine having a plurality of cylinders, an exhaust manifold for receiving combustion products from said cylinders, an exhaust pipe for conveying such products away from said manifold, and a spark control lever, of a flame detector positioned in said exhaust pipe for producing an electrical output when flame is incident thereon, a threshold device fed by said detector for eliminating electrical outputs of less than a predetermined amplitude, an amplifier fed by said threshold device, and servomechanism controlled by said amplifier for moving said lever to advance said spark when ame is incident upon said detector, said servomechanism including a solenoid having a plunger and an output coil fed by said amplifier, a valve chamber having an opening in the central portion thereof for receiving oil under pressure and a pair of drain openings at opposite ends thereof, and a pair of holes intermediate said central opening and said drain openings, a valve member slidable in said chamber and secured to said plunger, said member, in one position, effecting communication (l) between said central opening and one of said holes, and (2) between one drain opening and the other of said holes, said member, in another position, effecting communication (l) between said central opening and said other hole, and (2) between the other drain opening and said one hole, a piston chamber, a piston slidably mounted therein and connected to said spark advance lever, a spring urging said piston toward one end of said piston chamber, a conduit connecting said other hole to said one end of the piston chamber, and a conduit connecting said one hole to the other end of the piston chamber, the valve-piston assembly being constructed and arranged so that flame incident upon said detector causes said valve member to move to said other position, with resultant movement of said piston away from said one end of the piston chamber and advance of said spark control lever.

2. The combination, with an internal combustion engine having a plurality of cylinders, an exhaust manifold forreceiving `combustion yproducts from said cylinders, -an

Yexhaust pipe for conveying such Aproducts away from `said manifold, and a spark control lever, of a flame detector positioned in said exhaust pipe for producing an electrical output when vflame is incident thereon, a threshold device Afed by said detector for eliminating electrical outputs of less .thana predetermined amplitude, an amplifier fed by n'saidthreshold 4device, `and .servomechanism controlled by said amplifier for moving said leverto' advance said spark when flame is 'incident upon said detector, said servomechanism including a solenoid having a plunger and an output coil fed by saidamplier, apiston chamber, Aa piston slidably mounted therein and connected to said spark advance lever, a spring urging said piston toward one end of said piston chamber, Aa hydraulic valve controlled by said plunger to admit oil under pressure to :the other end of the piston chamber when said plunger is inone position and to'admit oil under pressure to said one end of the piston chamber when said plunger is in another position, the valve-piston'assembly being constructed and arranged so that ame incident upon said detector causes said plunger to move tosaidother position, with resultant movement of said piston away from said one end of the piston chamber and advance of said spark control lever.

3. The combination, with an internal combustion engine having a plurality of cylinders, an exhaust pipe for conveying combustion 'products'awayfrom said cylinders and a spark control lever, of a flame detector positioned in said exhaust pipe for producing an electrical output when flame is incident thereon, an amplifier fed by said detector, and servomechanism controlled by said amplifier for moving said lever to advance said spark when ame is incident upon said detector, said servomechanism including a solenoid having a plunger and an output coil fed by said amplifier, a piston chamber, a piston slidably mounted therein and connected to said spark advance lever, a spring urging said piston toward one end of said piston chamber, a hydraulic valve controlled by said plunger to admit oil under pressure to the other end of the piston chamber when said plunger is in one position and to terminate such ow of oil when said plunger moves to another position, the valve-piston assembly being constructed and arranged so that fiame incident upon said detector causes said plunger to move to said other position, with resultant movement of said piston away from said one end of the piston chamber and advance of said spark control lever.

4. The combination, with an internal combustion engine having a plurality of cylinders, an exhaust manifold for receiving combustion products from said cylinders, an exhaust pipe for conveying such products away from said manifold, and a lever regulating an operating variable of said engine which affects backfiring of a ame detector positioned in said exhaust pipe for producing an electrical output when fiame is incident thereon, an amplifier fed by said detector and servomechanism controlled by said amplifier for moving said lever to suppress backfiring when flame is incident upon said detector, said servomechanism including a relay, a piston chamber, a piston slidably mounted therein and connected to said spark advance lever, a spring urging said piston toward one end of said piston chamber, a hydraulic valve controlled by said relay to admit oil under pressure to the other end of the piston chamber when said plunger is in one position and to terminate such flow of oil when said plunger moves to another position, the piston assembly being constructed and arranged so that flame incident upon said detector causes said relay to move to said other position, with resultant movement of said piston away from said one end of the piston chamber and advance of said spark control lever.

5. The combination, with an internal combustion engine having a plurality of cylinders, a pipe in which fiame is present during an abnormal operating condition of said engine, and a lever regulating an operating variable of said engine which affects such abnormal operating condition, of a flame detector positioned in said pipe for producing an electrical output when ame is incident thereon, an amplifier fed by said flame detector, and servomechanism controlled by said amplifier for moving said lever to suppress said condition when ame is incident upon said detector, and the amplifier output is mined'level.

6. The combination, with an internal combustion engine having a pipe for conveying combustion gases there, from and a control lever regulating an operating variable of said engine which aects afterfiring, of a liame detector for producing an electrical output when a flame is incident thereon, said detector having a ceramic, generally hemispherical head portion positioned within said pipe, a generally cylindrical refractory, conductive shield having one end thereof secured to said head portion, saidV end of the shield having a plurality of circumferentially spaced openings formed therein through which protrude portions of said ceramic head, a .conductive electrode disposed within said shield and having a hook-shaped end portion embedded in said ceramic head, and an insert of refractory insulating material surrounding said electrode and disposed within said shield, whereby an electrical output is produced between said electrode and said shield when a ame is incident on said ceramic-head, a threshold device for rejecting components'of less than a predetermined amplitudein said electrical output, an amplifier fed by said threshold device, and servomechanism responsive to the output of said amplifier to shift said control lever in such manner as to eliminate afterfiring when the output of said amplifier is of greater than a predetermined amplitude.

7. The combination, with an internal combustion engine having a pipe for conveying combustion gases therefrom and a control lever regulating an operating variable of said engine which affects afterfring, of a liame detector for producing an electrical output when a llame is incident thereon, said detector having a ceramic head portion positioned within said pipe, a refractory, conductive shield having one end thereof secured to said head portion, and a conductive electrode disposed within said shield and having an end portion embedded in said ceramic head, whereby an electrical output is produced between said electrode and said shield when a flame is incident on said ceramic head, an amplifier for increasing the amplitude of said electrical output, and servomechanism responsive to the output of said amplifier to shift control lever in such manner as to eliminate afterfiring when the output of said amplifier is of greater than a predetermined amplitude.

8. The combination, with an internal combustion engine having a pipe for conveying combustion gases therefrom and a spark control lever, of a ame detector for above a predeterproducing an electrical output when a liame is incident thereon, said detector having a ceramic, generally hemispherical head portion positioned within said pipe, a generally cylindrical refractory, conductive shield having one end thereof secured to said head portion, and a conductive electrode disposed within said shield and having a hookshaped end portion embedded in said ceramic head, of refractory insulating material surrounding said electrode and disposed within said shield, whereby an electrical output is produced between said electrode and said shield when a flame is incident on said ceramic head, an amplifier for increasing the amplitude of said electrical output, and servomechanism responsive to the output of said amplifier to shift said spark control lever in such manner as to eliminate afterfiring when the output of said amplifier is of greater than a predetermined amplitude.

9. In combination, an internal combustion engine having a pipe in which ame is present during an abnormal operating condition of said engine, a flame detector having a ceramic portion positioned within said pipe, whereby an electrical output is produced between different points within said ceramic portion when a fiame is incident thereon, an indicator responsive to said electrical output, and conductor means connecting said different points in circuit with said indicator.

10. In combination, an internal combustion engine having a pipe for conveying combustion gases therefrom, a

Hamel-detector having a ceramic head .positioned within said pipe, a refractory, conductive shield having one -end thereofsecured -to"said head portion, and a Aconductive electrode'disp'osed'fwithin' said shield and yhaving-an end portion' embedded in said ceramic head, whereby anrelectrical output yis produced between said electrode and-said s'hieldwh'e'n a a'me lis incident Yon said ceramic head, and an -indic'atorresponsive'to said electrical output, said indicatorbeing connected vin circuit with said 4electrode and said-Shield.

11. In combination, an internal combustion'engine having'fa pipe for 'conveying combustion gases therefrom, a ame 'detector having a ceramic portion positioned within said='pipe,` whereby an electrical output is'produced between d'iiferent points within said ceramic portion'when a'ame is incident thereon, an indicatorresponsive to'said 4electrical output, and'conductor means connecting `said Id'ifferentpoints in circuit with said indicator.

12. In'cornbination, an'internal'combustion engine having an intake manifold for conveying a fuel mixture' to the intake valves of the cylinders, a ame detector having a ceramic portion positioned in said manifold, whereby an 'electricaloutput is produced between different `points within'said ceramic portionwhen a ame is `incident thereon, an lindicator responsive to said electrical output, and con- 5,8 ductor means connecting 'said diiferentpoints incircuit with vsaid indicator.

13. The combination, with an internal/combustion engine having yan intake manifold :for conveying a-fuel mixture to the -intake val-vesof thecylinders, of -a flamez detector positioned in the intake ymanifold for producing 'an electrical output when a'arne'is incident thereon, said detector having a ceramic portion positioned in said manifold, whereby -an felectrical output is produced between dilerentpoints withinv said :ceramicportion when aame is incident thereon, a control lever regulating yan operat ing variable of said engine-which-effects backring, and means responsive to a predetermined electrical output lbetween said different points of fsaid detectorto move said control lever in such fashion as to suppress backfiring.

References Cited in the ile of this patent UNITED STATES PATENTS 20 2,053,121 Vayda Sept.' 1, 1936 2,248,090 Kittler July l8, 1941 2,251,751 Minter Aug. 5, 1941 2,295,455 Dillman Sept. 8, 1942 2,355,090 Love et al Aug. 8, 1944 

